Is the morning peak of acute myocardial infarction's onset due to sleep-related breathing disorders? A prospective study

Many studies have shown that the risk of experiencing a myocardial infarcti on (MI) is increased during the first hours of the morning. Sleep apnea syn drome (SAS) is associated with an enhanced adrenergic activity, prolonged a few hours after awakening. We aimed at assessing whether sleep breathing d isorders could be a culprit for the morning excess rate of MI. We studied 4 0 middle-aged men admitted for an acute MI. An overnight polysomnographic s tudy was performed 37.4 +/- 9.4 days after the MI. The prevalence of SAS wa s high (30%). The prevalence of SAS was significantly higher in patients wi th the MI onset during the morning. The circadian pattern was significantly different in patients with or without SAS: those with SAS presented an imp ortant peak of MI onset during the period between 06.00 and 11.59 h. None o f them had their MI during the period between 24.00 and 05.59 h. This diffe rent nyctohemeral pattern underlines the potential role of sleep breathing disorders as a trigger of MI. Copyright (C) 2001 S. Karger AG, Basel.